1. Field of the Invention
The invention relates to a wafer lens unit and a method for manufacturing the wafer lens unit.
2. Description of the Related Art
Currently, portable terminals of electronic device such as mobile phone and PDAs (Personal Digital Assistant) are equipped with image pickup units which have small and thin shapes.
Such image pickup units generally include a solid-state image pickup device such as a CCD (Charge Coupled Device) image sensor ora CMOS (Complementarray Metal-Oxide Semiconductor) image sensor, and lenses that form an image on the solid-state image pickup device. As mobile terminals become smaller and thinner, the image pickup units mounted on those are also required to achieve reduction in size and thickness. In order to decrease the cost of the portable terminals, improvement of productivity is desired. As a method for manufacturing such small lenses in large numbers, known is a method for lenses module comprising producing a wafer lens array comprising a substrate section and a plurality of lenses on the substrate section, cutting the substrate section to form pieces comprising a lens. By the method, lens modules can be mass-produced. Also known is a method for mass-manufacturing an image pickup unit comprising integrally combining a substrate section in which a plurality of lens sections are formed and a sensor substrate in which a plurality of solid-state imaging pickup device was form formed and cutting the sensor substrate with the substrate so that the unit comprises a lens and a solid-state imaging pickup device.
Heretofore, as the references concerning the wafer lens, knows are JP-T-2005-539276, WO07/107025, JP-A-H7-248404, and JP-A-2003-294912. JP-T-2005-539276 discloses a multilayer-structure comprising stacked wafer lenses which comprise a substrate and a plurality of lenses on the substrate. WO07/107025 discloses a method comprising feeding formation material on a substrate to form a lens on the substrate using a mold. As is different from the above wafer lens, a known article comprising a plurality of lenses is a micro lens array which does not integrally connect with the substrate. JP-A-H7-248404 does not use a mold for forming lenses since a resin layer which is formed on one side of a substrate is pressed and cured with a substrate comprising holes. JP-A-2003-294912 discloses a technique for forming a micro lens array comprising a two-layer structure, wherein the axes of the two layers adjusted to correspond to each other.